Vitamin D appears to protect women under the age of 75 from developing age-related macular degeneration, according to a U.S. study of more than 1,300 women.

The condition leads to the loss of a person's central field of vision as a result of a degenerating macula — a small spot on the eye's retina where vision is sharpest.

"[It] is the leading cause of adult irreversible vision loss in developed countries," the researchers write in a background document to the study, published in the April issue of Archives of Ophthalmology.

Researchers at the University at Buffalo, New York, measured the blood levels of vitamin D in 1,313 women. After adjusting for age and other known risk factors, they found that in women younger than 75, higher blood levels of vitamin D was associated with a significant decreased risk for the condition.

Women who consumed the most vitamin D saw their odds of developing early macular degeneration decrease by 59 per cent, compared with women who consumed the least vitamin D.

The top food sources of vitamin D in the sample were milk, fish, fortified margarine and fortified cereal. No relationship was observed using self-reported time spent in direct sunlight.